Summary/Abstract Modification of risk factors currently offers the best hope of preventing cognitive decline and reducing the growing global burden of dementia. While a number of potential protective or risk factors for Alzheimer's disease (AD) and dementia have been identified, further research is needed to better understand the causal pathways and underlying mechanisms. In this application, we propose to study in-depth three key hypothesized modifiable risk factors of cognitive decline and dementia?low educational attainment, cardiovascular health, and ambient air pollution?taking advantage of newly available data from the Longitudinal Aging Study in India (LASI), a nationally representative, multi-disciplinary survey of older Indians (i.e., those aged 45+). Studying these issues in the context of India is particularly important and valuable because of the rapid aging of the Indian population, as well as the potential contributions to a better understanding of the causal pathways of life-course risk and protective factors. India provides an excellent epidemiological ?laboratory? to study key modifiable risk factors for cognitive health. Because state governments in India have diverged in their policies, rates of economic growth, and investments in education, there is plausible exogenous variation in access to schooling, which provides a unique opportunity to study the potential causal effect of education on late-life cognitive health and risk of dementia. The high prevalence of cardiovascular risk factors (e.g., hypertension, diabetes, and hyperlipidemia) and extremely high levels of ambient air pollution in certain cities in India provide an unparalleled opportunity also to study these important risk factors. From the pilot LASI data, we observed that older women are at a cognitive disadvantage in India, whereas older women have a cognitive advantage in developed countries like the United States. We aim to study the contributors to gender differences in late-life cognition, focusing especially on the roles of educational attainment and discrimination against women, both of which vary greatly by geographic region and caste. Our final aim is to make all compiled and linked data widely and publicly-available for research. From printed historic government records, we will compile time-and-location specific data on access to education. Using GPS information, we will link LASI data to air pollution exposure data. We will perform bioassays of venous blood specimens to obtain a wide-range of biomarkers in addition to the markers already collected during the main LASI study fieldwork. The proposed work is innovative in its aim to study key modifiable risk factors for late-life cognitive health, using newly-collected rich, nationally-representative data for the first time in India. The findings of this investigation will yield new insights on preventable risk factors for dementia, as well as policy implications for promoting cognitive health and reducing the burden of dementia in India and beyond.